1. Field of the Invention
The present invention relates to a light emitting diode (LED) module for lighting, in which a waterproof agent is applied on terminals exposed between a printed circuit board (PCB) and LED elements on the PCB, thereby preventing erosion of the terminals caused by the permeation of water.
2. Description of the Related Art
LED elements are referred to elements which generate minority carriers (electrons and holes) injected by using a p-n junction structure of semiconductor and then recombine them to emit light. As for the LED elements, there are provided red LED elements formed of GaAsP or the like, green LED elements formed of GaP or the like, and blue LED elements using InGaN/AlGaN double hetero structure.
The LED elements have low power consumption and a long lifespan. Further, the LED elements can be installed in a narrow place and have a strong characteristic against vibration. Such LED elements are used as display elements and backlights. Recently, studies are being actively conducted to apply the LED elements to the use of general lighting.
The LED elements for lighting can be installed in outdoor places or in a pond or river so as to provide a beautiful view to people in the night. Further, the LED elements can provide light in the water such that divers can easily do their jobs under the water.
However, when LED lightings are installed in outdoor places, they should satisfy such a condition as to operate in various environments (weather conditions). When the LED elements are operated in accordance with a weather condition after being mounted on a PCB, the LED elements can endure a change in temperature, but may be damaged by the cut-off or short-circuit of circuits caused by the permeation of water during the rainy season.
Further, when the LED lightings are applied to lightings under the water, an electric shock may occur due to an electric leakage, and they may be easily discharged. Therefore, a structure for preventing water from permeating is separately manufactured, which can house the LED lightings, and is then completely filled with a waterproof agent such as epoxy or silicone, thereby preventing water or moisture from permeating into the structure. Further, since the entire inner portion of the structure should be molded and the structure should be separately manufactured, the volume of the LED module increases, and a manufacturing cost increases.
FIG. 1 is a schematic cross-sectional view of a conventional LED lighting to which a waterproofing structure is applied.
As shown in FIG. 1, the LED lighting 10 which can be used under the water includes a plurality of LED elements 11 mounted on a PCB 13 and a waterproofing structure 15 which houses the LED elements 11.
Inside the waterproofing structure 15, a waterproof agent 17 which is formed of epoxy or silicone and transmits light is filled. The waterproof agent 17 prevents water from permeating into the waterproofing structure 15 from outside, thereby protecting the PCB 13 and the LED elements from the water which causes erosion and electric leakage.
As described above, the LED lighting 10 has an advantage of preventing water from permeating by using the waterproofing structure 15 and the waterproof agent 17. However, since the waterproofing structure and the waterproof agent are used, the volume of the LED lighting 10 increases, and a manufacturing cost increases.
Further, since the waterproof agent 11 is filled on the entire top surfaces of the LED elements 11, some of lights generated from the LED elements 11 are absorbed while passing through the waterproof agent 17. Further, since the propagation direction of the lights is bent, the range of light emission is narrowed, and luminance efficiency decreases.
Further, since the waterproof agent 17 is applied on the entire surfaces of the PCB 13 and the LED elements 11, heat generated from the LED elements 11 is not smoothly radiated because of the waterproof agent 17. Therefore, the lifespan of the LED elements is reduced.